1. Field of the Invention
The present invention relates to a fringe field switching mode transflective liquid crystal display. More particularly, the present invention relates to a fringe field switching mode transflective liquid crystal display capable of displaying high quality images with wide viewing angles.
2. Description of the Prior Art
As generally known in the art, liquid crystal displays are classified into transmissive liquid crystal displays using backlight units as light sources thereof and reflective liquid crystal displays using natural light as light sources thereof. Since the transmissive liquid crystal display employs the backlight unit to generate light, it can display bright images in dark places. However, such a backlight unit may increase power consumption of the transmissive liquid crystal display. In contrast, the reflective liquid crystal display uses natural light as a light source without employing the backlight unit, so it can display images with low power consumption. However, the reflective liquid crystal display cannot be used in dark places.
To solve the above problems of the transmissive and reflective liquid crystal displays, transflective liquid crystal displays have been suggested. The transflective liquid crystal display can be selectively used as a transmissive liquid crystal display or a reflective liquid crystal display depending on operational environment thereof, so it can display images with relatively low power consumption in the bright places while displaying images by using the backlight unit in the dark places.
Conventional transflective liquid crystal displays have a single cell gap structure in which a cell gap (dt) of a transmissive area is identical to a cell gap (dr) of a reflective area as shown in FIG. 1, or a dual gap structure in which a cell gap (dt) of a transmissive area is larger than a cell gap (dr) of a reflective area by approximately two times as shown in FIG. 3. In FIGS. 1 and 3, reference numerals 1, 2a, 2b, 3, 4, 5 and 6 represent a lower substrate, a pixel electrode, a reflective electrode, an upper substrate, a common electrode, liquid crystal and an organic insulative layer, respectively.
However, according to the conventional transflective liquid crystal display having the single cell gap structure as shown in FIG. 1, a phase delay (Δn·d) of the reflective area is twice larger than that of the transmissive area, so that a V-R curve in a reflective mode does not match with a V-T curve in a transmissive mode as shown in FIG. 2, thereby causing incorrect grayscales and inferior electro-optical characteristics of the liquid crystal display.
For this reason, the conventional transflective liquid crystal display having the dual cell gap structure has been recently used. According to the conventional transflective liquid crystal display having the dual cell gap structure, although the cell gap of the reflective area is about a half of the cell gap of the transmissive area, an optical path of the reflective area is twice larger than that of the transmissive area, so that the phase delay of the reflective area is identical to that of the transmissive area. Thus, as shown in FIG. 4, the V-R curve may easily match with the V-T curve. Accordingly, the conventional transflective liquid crystal display having the dual cell gap structure can prevent the incorrect grayscales while improving electro-optical characteristics thereof in comparison with the conventional transflective liquid crystal display having the single cell gap structure.
However, the conventional transflective liquid crystal display having the dual cell gap structure may present a great step difference, which is twice larger than that of the conventional transflective liquid crystal display having the single cell gap structure, due to a cell gap difference between the transmissive area and the reflective area, so the liquid crystal may be unevenly aligned. For this reason, it is difficult to fabricate the conventional transflective liquid crystal display having the dual cell gap structure, so that productivity thereof may be lowered. In addition, the liquid crystal adjacent to an alignment layer may be incompletely aligned as an electric field is applied thereto, thereby causing narrow viewing angles.